Peptide Ang-(1-7) and its receptor MAS in ovulatory initial process of bovines

Researchers from Universidade Federal de Santa Maria, Santa Maria, Rio Grande do Sul, Brazil, found that peptide Ang-(1-7) and its receptor MAS do not have function at the beginning of the ovulatory process in cattle as it has in other multiovulares species such as rabbits. The research was published in Ciência Rural journal, v.42, n.10, of October 2012.

To reach this result, researchers conducted two experiments. In the first experiment, they used an in vitro model of follicular cell culture and evaluated the effect of treatment with Ang-(1-7) or blockade of MAS receptor by inhibitor d-Ala7-Ang-(1-7) (a-779) in the expression of mRNA for epirregulina (ereg, an early marker of the process of ovulation) in granulosa cells. In the second experiment, the researchers used an in vivo model of intrafollicular injection in which 20 cows had their estrous cycle synchronized. When the follicles reached a minimum of 12 mm diâmtro, researchers conducted the intrafollicular injection of A-779 or 0.9% saline solution. At the time of injection, there was an IM application of GnRH analogue to induce ovulation.

The results showed that supplementation with Ang-(1-7) or blocking its receptor MAS in a culture system of granulosa cells did not alter the pattern of mRNA expression for Ereg. The intrafollicular application of A-779 (10-5M) did not block ovulation, when carried out before the expected peak of LH, which suggests that Ang-(1-7) has no role in the cascade of early ovulationp.

The study breaks new ground by being the first study of the system function Ang-(1-7) / MAS in monovular specie, using models in vitro and in vivo. Other studies have described the operation of multiovulares species such as mice and rabbits. According to researcher Bernardo Gasperin, the study results may support a better understanding of the physiological process of ovulation in cattle and can contribute in biotechnologies applied to reproduction and understanding of ovarian pathologies in animal and human species.